Irrespective of its function, a switching device unit is generally also referred to as a consumer branch and is usually arranged next to further consumer branches on a standardized top-hat rail in a switchgear cabinet. The consumer branches that are arranged in a switchgear cabinet are assembled in a modular construction in order that the respective requirements can be met. Such consumer branches are used in particular in industrial plant engineering for controlling and switching high currents and voltages. In particular, a three-phase motor is driven using the switching device unit. In this case, the switching device unit is also referred to as a reversing starter or motor starter.
The switching device unit of one or more consumers usually has three functions for the protection of the consumer or consumers. The first function relates to the operational switching of the consumer, usually the motor, and is realized by means of a separate standard module, usually a so-called contactor. The contactor is designed for the purpose of repeatedly switching high currents on and off for operational use.
Furthermore, the functions for short-circuit protection and overload protection in a switching device can be integrated in a standard module which is referred to as a circuit breaker. The circuit breaker separates the consumer from the network if a short circuit occurs or if an excessive current is present. According to the prior art, the different functions are usually performed by different standard modules which are arranged next to each other on a chassis.
WO 03/043156 A1 discloses a control and protection module for a multipole low-voltage switching apparatus, which module consists of a mounting plate, a control electromagnet and a trip element, these being provided to act on mobile contacts for the purpose of opening or closing power terminals. In this case, the control and protection module uses the same number of switching elements or current trip elements as there are power terminals.